The present invention relates to a cordless telephone system or similar mobile radio communication system which limits the service available for a radio terminal in an exclusive zone allocated to the terminal and removes the limitation in a common zone while opening all the zones to a particular radio terminal.
The installation of a cordless telephone system in offices is spreading. A service area covering an office is usually wider than one covering a home, it is divided into a plurality of radio zones. In this kind of system, a particular zone identification (ID) signal is assigned to each radio zone together with a common system ID code. The zones where individual radio terminals are positioned are registered to control the correspondence between the zone ID codes and terminal ID codes. Each terminal, therefore, can be serviced with no regard to the location so long as it lies in the service area. However, assuming a single building accommodating a plurality of tenants, e.g., companies, charges and user rights have to be taken into account. Then, it is necessary to limit the service area where a radio terminal can be used on a company basis. Should all the radio terminals belonging to the system be used in any place inside the building, a radio base station assigned to a certain company might be used illicitly by radio terminals belonging to the other companies. On the other hand, when the service area available for a company is limited on a floor basis, radio terminals owned by a company cannot be used in a common space inside the building, e.g., restaurant or lobby. Further, such a configuration limits even the service area available for a radio terminal used by, for example, a guard inside the building despite the fact that the role of such a particular terminal should be shared by all the other terminals.